ENHANCED PABX SYSTEM WITH REROUTING/LOGGING SYSTEM Esther Tina Escolastico, Niña Rica Hernandez, John Alexander Rhoss Largo, Rhett Francis Mallen, Charo Anne Marasigan, Jian Carlo Reyes, Edsel Uy, and Januel Mikel Venturanza V – BS ECE In partial fulfillment of the requirements in ECE 191.2 March 3, 2003

OBJECTIVE OF THE STUDY To implement a PABX system servicing the rooms under the ECCE department The system should be able to route calls to a person’s location/room at a certain time Signals used in the public exchange should be the ones implemented in the system To interface the physical system to a central computer for control, administration and decision-making

BACKGROUND Private Branch Exchange (PBX) replaced by Private Automatic Branch Exchange (PABX) in the 1960s Introduction of PABX Need for flexible telephone systems that can be expanded or innovated to cater to specific consumer needs Automatic switching of calls between local-loop users while allowing access to (an) external phone line(s)

BACKGROUND Introduction of PABX (cont’d.) Ateneo scene Automatic routing of calls to appropriate recipients while recipients can also communicate w/ the other users in the local network Ateneo scene Challenge: mobility of teachers High rate of dropped and/or unanswered calls

WHY THE NEED? All consumer needs and/or requirements are not always satisfied Level of specificity that available g&s are unable to meet. A regular PABX only diverts calls to local numbers assigned to local telephone units/lines. End-users in a university are usually on-the-go

PARTS OF ENHANCED PABX A - Analog Module 1 - Local loop 2 - Loop-current detector 3 - Interface to public/Ateneo exchange 4 - Connection switches for the phone lines 5 - Switch for the different functions 6 - DTMF decoder 7 - Signal generator for the different functions.

PARTS OF ENHANCED PABX B - Software Module C - Interface Module 1 - Main control program 2 - Database 3 - Voice prompt C - Interface Module 1 - Optoisolator 2 - OR gates 3 - Latches/Decoder

SOFTWARE DESIGN

SOFTWARE DESIGN A. Main Control Program

SOFTWARE DESIGN B. Database PABX system database contains the necessary information about the client like his/her name, the room where he/she is logged in, client identification code Uses Microsoft Access database format data control allows us to move through the records in a record set thus making the database search possible

SOFTWARE DESIGN Once a Match is found, system will send Ring/Ringer signals to the two parties Otherwise, Busy signal will be sent

SOFTWARE DESIGN C. Voice Prompt Module voice prompt is only applied to Tel_5, the PLDT phone line Instead of sending a dial tone to it, a voice prompt is put in place Used to facilitate incoming calls

Optoisolator

Latches and Decoder When the decoder is enabled, 3 Binary Select inputs (A0, A1and A2) determine which one of the outputs (O0–O7) will go . When enable input E3 is held LOW or either E1 or E2 is held HIGH, decoding function is inhibited and all outputs go HIGH. In our circuit, we connected the enable input E3 to the control coming from the parallel port. This control manipulates whether the decoder and latches circuit will be used or not. Enable input E1 and E2 are always connected to the ground. The outputs of the decoder are first pass to the inverters. This is because the outputs are used to enable the latches, which are active high.

CONCLUSION standard PABX system simply directs calls without the use of an intelligent decision-making scheme ordinary system, calls are simply directed to a phone unit with an assigned local number builds on this principle by adding a database from which the central control determines the routing destination of a call

CONCLUSION project integrated learnings from the subjects taken before, like Digital Design, Microprocessor Systems, Electronics I and II, coupled with new knowledge in programming languages like Visual Basic 6.0 and Turbo Debugger

RECOMMENDATIONS PABX system developed in this study can be integrated with the databases of log-in systems for further efficiency, the system can be expanded to include commercial features such as call waiting, call conferencing, call forwarding, and call diverting system could be redesigned to accommodate more subscriber lines